High definition television apparatus



March 5, 1940. HARDING, JR 2,192,376

' HIGH DEFINITION TELEVISION APPARATUS Filed July 17, 1936 4 Sheets-Sheet 1 INVENTOR ROBERT HARDING, Jk.

JMLMW 062 ATTORNEYS Mai-ch 5, 1940.

HIGH DEFINITION TELEVISION APPARATUS Filed July 17, 1936 4 Sheets-Sheet-Z ATTORNEYS R. HARDING, JR 2,192,376

March 5, 1940. R. HARDING, JR v 2,192,376

HIGH DEFINITION TELEVISION APPARATUS Fild July 17, 1936 4 Sheets-Sheet a INVENTOR RQBERT HARDIN JR ATTORNEYS March 9 v R. HARDING. JR 2,192,375

HIGH DEFINITION TELEVISION APPARATUS Filed July 17, 1936 4 Sheets-Sheet 4 INVENTOR ROBERT HARDJNQ]:

BY M W /Q ATTORNEYS Patented Mar. 5, 1940 UNITED STATES PATENT OFFICE 2,192,376 HIGH DEFINITION TELEVISION APPARATUS Application July 17, 1936, Serial No. 91,083

9 Claims.

This invention relates to television apparatus and has for its principal object to provide an apparatus for improving the definition of the image transmitted and received.

Another object of the invention is to provide a television apparatus by means of which the dark lines usually formed between scanning lines of a picture are eliminated.

Another object of the invention is to provide a helical mirror drum which in itself will tend to improve the definition and decrease the formation of dark lines.

Another object of the invention is to provide a helical mirror drum with a plurality of separate :groups of scanning elements displaced with respect to each other in a direction perpendicular to the direction of scanning.

Still another object of the invention is to provide' an oscillating optical device to cooperate with a scanning apparatus to slightly shift successive images scanned thereby.

Other objects and objects relating to the method of constructing and assembling the various parts will be apparent as the description of the invention proceeds.

The invention is illustrated in the accompanying drawings, in which:

Fig. l is an elevational view of a helical mirror drum television receiving apparatus embodying the invention;

Fig. 2 is a sectional plan view of the drum shown in Fig. 1 and taken on the line 2--2 of that figure;

Fig. 3 is a sectional elevational View of a portion of the plates of Fig. 2;

Fig. 4 is a plan view of a modified form of the drum of Figs. 1, 2 and 3;

Fig. 5 is an isometric view of a group of the plates of Fig. 4;

4 Fig. 6 is a sectional elevational view of a portion of the plates of Fig. 4 taken on the line 6-6 of that figure;

Figs. 7, 8, and 9 are plan views of the three plates shown in Fig. 5;

Fig. 10 is a plan view of a television transmitter incorporating either of the drums of Figs. 1 to 9 inclusive;

Fig. 11 is an elevational view partly in section of a modified form of the receiving apparatus shown in the previous figures; and

Fig. 12 is a front elevational view of the shutter of Fig. 11.

In television apparatus where the picture is scanned in successive lines complete scannings of a picture are repeated usually at the rate of 20 per second or higher, each successive scanning of the picture reproducing the same number of picture lines in the same sequence, or, if not in the same sequence, at least with the lines coinciding, so that all of the lines of one picture 5 fall exactly over the lines of a preceding picture.

Broadly the present invention provides for a slight shift of the position of the picture lines for successive pictures, this shift being preferably, but not necessarily, less than the width of 10 one picture line. According to the invention, 11' picture line No. 1 falls at the top edge of the picture for one complete scanning, the same picture line for the second complete scanning will be positioned about one-half a picture line down, 1

which it will be more accurately defined.

One way of carrying out this invention is 11- lustrated in Fig. l in connection with a scanning device of the helical mirror drum type. A helical mirror drum I0 may be mounted upon the shaft H of a motor which may be of the syn- 30 chronous type or may be driven at a constant predetermined speed by synchronizing apparatus, not shown. The mirror drum I0 may be somewhat similar in construction (except for the modification forming the invention) to that shown in the patent to Gardner No. 1,753,697. This drum comprises a plurality of plates mounted in stacked relation on the shaft H and held thereon by a disc at the lower end which may rest upon a shoulder formed in the shaft 5 I, and a disc at the top of the drum held in place by a suitable nut l6.

A modulatable light source I! may be positioned at a predetermined distance from the drum Ill and may preferably take the form of a line of light which is arranged parallel to the axis of the drum. The lamp may comprise a tubular portion l8 of relatively small cross-section mounted between two bulbs l9 and 20 in which may be positioned respectively a cathode 2| and an anode 22. These electrodes may be made of some suitable metal, such as nickel, which may be easily degasified, and I prefer to make the cathode with an exceptionally large amount of active surface. I 55 then "comprises the edges of two plates.

to form the first'refle'cting surface 27.

The two bulbs l9 and 20 and the tubular portion I8 form a single envelope which may be filled with an ionizable gas, such as neon, at a reduced pressure and in addition may contain a small amount of mercury. The lamp is adapted to be operated on the output of a radio set 23 provided with antenna connection 24 as shown.

One such lamp to give, good results had a tubular portion l8 about 9 inches long with an outside diameter of about A; inch. The bulbs l9 and 20 measured about an inch and a half in diameter and the lamp was filled with neon at about 10 mm. of mercury pressure with the addition of a small drop of mercury. The cathode of this lamp was formed of nickel wire mesh, a strip about one inch wide and 10 inches long being rolled up into a cylinder and secured in the bulb it upon the press. The anode 22 was formed of a small cup-shaped piece of sheet nickel.

The drum is intended to be viewed subjectiv'ely, the observer seeing the television image in the drum itself asthe reflecting edge of each plate picks up a portion of the tubular light source I8 and causesit to sweep across the mirror surface in the opposite direction to the rotation of the mirror drum.

In accordance with the present invention I may use two reflecting surfaces on each plate, so that as the drum rotates there are two complete scannings of the picture in succession, and by a novel arrangement of the plates I position each refleeting surface of the second series in a plane corresponding to the plane of the line between two reflecting surfaces of the first series. In order to accomplish this result I use twice as many plates as in the Gardner patent referred to above, making the thickness of each plate one-half what it would normally be. Each reflecting surface But the plates are not identical, there being two sets. One set of plates has the two reflecting surfaces parallel to each other, while with the other set the surfaces are at a certain predetermined angle.

The first two upper plates 25 and 26 (Figs. 2 and 3), representing one plate of one set and one of the other set, have their left sides aligned In like manner, the second twoplates 28 and 29 (Fig. 3) have their two left reflecting edges aligned to form the reflecting surface 30 which corresponds to the second line of the picture, and so on for all'of this group of the reflecting surfaces of the drum. The right reflecting edges'of plates 25 and 26 however are not aligned but bear an angle to each other equal to the angular relation be-,

tween the reflecting surfaces 21 and 33.

The top plate 25 has a reflecting surface M on the right side which may be parallel to the left hand surface 21, but the plate 26 has a reflecting surface 32 on the right side of the plate which forms an angle to the surface 3i equal to the angular spacing between the pairs of plates.

If the apparatus is designed to produce a 60 line picture, the left hand reflecting surfaces of the uppermost plates 25 and 26 form the edge 21, which makes the first line of the picture, and the left hand'edges of the second two plates 23 and 29 coincide to form the reflecting surface 343 which may be rotated through an angle of 3 in a counterclockwise direction as viewed in Fig. 2. The edge 3! of the plate 25 is parallel to the edge 21 thereofbut the edge 32 of the plate 26 is rotated 3 from the edge 3! of the plate 25 and coincides with the right hand edge of the plate 28 which is aligned to form the reflecting surface 33 which forms the first line of the second. helix, the right hand edges of plates29 and 34 forming the refleeting surface 35 which corresponds to the second line of the second reflecting helix.

It will thus be seen-that the first line represented by the surfaces 33 is even with the dividing line between the two reflecting surfaces 21 and 33, or the first two picture lines formed by the first helix. With this arrangement there will be two-complete scannings of the picture with one rotation of the drum, and hence for a rateof 20 pictures per second, which may be assumed by way-of example, the motor would'be operated at 600 R. P. M. Means for-obtaining a greater angle between refl'ecting'surfaces with a higher speed of the motor, and-with certain consequent advantages, will be hereinafter described.

It will be understood that the same shifting of successive picture lines shouldbe carried out at the transmitter as has been described -for the When the mechanism is correctly operated, the first scanning at the'receiver, -pro-' duced by the rotation of the drum, will produce receiver.

an assembled television picture, while the second scanning produces lines slightly lower than the lines of the first. The picture, howeverywill not move downwardly as the second scanning at the transmitter has also taken place slightly lower with respect to the first scanning. The effect is to increase the definition as'already described and to eliminate any tendency to form dark lines between adjacent picture lines' With the arrangements of Figs. 1, 2, and 3 I spacethe plates at such angles that each helix I am not limited to two, however; as'any There will therefore be three will completely scan the picture when the drum has rotated through 120 prone-third of a complete rotation. With this arrangement I use three plates for each reflecting surfa'ce andI "design the plates so that the completerefle'cting surfaces are displaced V; the width of apicture line" .60 ready described for the-plates-with two' reflecting In such an arrangement oftriangular" for each helix, in a manner similar to that-alsurfaces. plates, if plate 35 represents-the uppermost plate, then this plate will have a reflecting" surface 31, a reflecting surface 38;- making an angle of 62 with the surfacefl, and-a reflecting surface 39,.

making an angle of with the surface-38-and 58 with the surface 31.

The second plate llthas a surfacedl which is exactly aligned with the surface 31 of the plate 36, and a surface 42 which has an angle of 60 7 with the surface M, or, in other words,-a 2 rotation from the surface'38 of the plate 33. The

third reflectingsurface-43 lies flush with the :surface 39' of the plate 36 and therefore has an angle of 62 with the surface 42 and 58 with the surface 4|.

The third plate 44 has a surface also in alignment with the surfaces 31 and 4| of plates 36 and 49 respectively, and a surface 46 which is in alignment with the surface 42 of the plate 40 and therefore makes an angle of 60 with the surface 45. The third surface ,4! is spaced at an angle of 2 from the aligned surfaces 39 and 43 respectively of plates 36 and 40 and therefore makes an angle of 60 with the edge 45 and 60 with the edge 45.

The plates are arranged in groups'of three as shown in Figs. 4 to 9, and these groups are then spaced at 2 apart for the entire 60 groups. When so positioned it will be found that the reflecting surfaces forming the lines of the picture for the second helix will be spaced /3 of a picture line down, while the picture lines formed by the third reflecting helix will be spaced of a picture line down. Thus the picture lines of the three successive pictures do not fall on the same horizontal position and the objects of the invention are attained. Of course, the transmitting apparatus must also be arranged to displace the picture lines for successive pictures through the same distance and in the same order.

In Fig. 10 a television transmitter is shown which makes use of either of the types of drums shown in Figs. 1 to 9 inclusive. Here the drum 5?) is rotatably mounted on a vertical shaft, similarly to the arrangement of Fig. 1, and an image of the person 5| to be televised is projected by means of an optical system 52 towards the drum 5D. A plate 53 provided with a slit 54 arranged parallel to the axis of the drum is positioned so as to receive light by reflection from the drum and the image of the person 5! is focused upon the plate 53. The person 5| may be illuminated by the electric lights 52', and each reflecting surface of the drum 5!) will cause one line of the image to move across the plate 53 as the drum rotates. Inasmuch as only a small portion of the light from this picture line can pass through the slot 54 the photo-electric cell 55 will receive the picture elements of the line in succession. The photo-electric cell 55 may be connected to a radio transmitter 55 provided with a suitable antenna 51 for radiating the television signal.

In connection with the foregoing figures I have shown mirror drums which are adapted to make more than one complete scanning of the picture for one rotation of the drum, but it may be desired to increase the angle between the mirror surfaces so as to permit closer positioning of the light source and therefore obtain a brighter picture. This may be accomplished by permitting the helices to pass more than once around the surface of the drum, but provision must be made at the same time to prevent all but one mirror surface from reflecting light to the observer at a time. Where the helices of reflecting surfaces pass around the .drum more than once there will always be more than one reflecting surface facing the observer which would produce several images in overlapping relation unless suitable arrangement is made for blocking out light from all but one surface.

In Figs. 11 and 12 I have shown one simple apparatus for operating a receiver in this manner. In this figure the drum which may be any of the drums already shown and described except that the plates have greater angular spacings and the helices are arranged to pass more than once around the axis of the drum, may be mounted on the driving motor 6| as indicated.

A light source 62 may be positioned at a suitable distance from the drum 6t, and between the light source and the drum I provide a shutter 63 which may be rotated at a constant speed from the driving motor 6| by means of the driving mechanism 64. This shutter has a plurality of slots 65 provided therein which are arranged at such an angle and are so shaped that only a portion of the light from the source 82 is permitted to strikethe drum. The speed of the shutter is arranged with respect to the speed of the drum so that the uncovered portion of the light source will be in line with that reflecting surface which it is desired to use at that time.

The arrangement ofthe shutter with greater spacing of the plates on the drum is shown and described in my copending application Serial No. 715,054 filed March 12, 1934 and is illustrated here for the purpose of showing the adaptability of the staggered picture lines for successive pictures with the greater angular spacing between plates.

With the mirror drums of Figs. 1 to 11 inclusive the displacement between the same picture lines of successively scanned pictures is preferably less than the width of one picture line, although greater displacement may be provided if desired.

Any of the scanning devices shown for the transmitter may also be used for the receiver and Vice versa,-as long as the amount of displacement for the lines is the same for both the transmitter and receiver. For the television receivers a particular type of television lamp has been illustrated and may be preferred, but other lamps may also be used, as long as the light thereof will freely follow the signal. Also the receiving apparatus may be designed to project a picture upon a screen While still maintaining the displacement of lines, as described.

Many other modifications may be made in the apparatus as shown and described and I do not therefore desire to limit myself to what has been shown and described except as such limitations are included in the appended claims.

What I claim is:

1. A television system comprising, in combination, a helical mirror drum having a plurality of mirror surfaces arranged in a plurality of helices around the axis of said drum, the reflecting surfaces of one helix being displaced one-third the width of one picture line slightly axially of said drum with respect to the mirror surfaces on another helix, means to scan an object field with said drum, means to translate the variations of light produced by said scanning means into electrical impulses, means to transmit said impulses to a remote point, means at said remote point to translate said electrical impulses into variations of light, means to repeatedly scan said variations of light, means to displace the picture lines of one complete scanning from the picture lines of the next successive complete scanning, said displacement being equal to'the displacement of the reflecting surfaces of one helix on said mirror drum from those of another helix.

2. A television system comprising, in combination, means to repeatedly scan an object field to form a plurality of picture lines, the picture lines of one complete scanning being displaced a distance equal to one-third the width of one picture line, means to translate the variations of light produced by said scanning means into electrical impulses, means to transmit saidele'ctric'al impulses to a remote point, meansat said remote point to translate said electrical impulses into variations of light, a helical mirror drum mounted adjacent said translating means, said drum comprising a plurality of reflecting surfaces arranged in a plurality of helices around the axis of said drum, each of said surfaces representing 10" one line of the reproduced picture, the surfaces of one helix being displaced axially of the drum with respect to the surfaces of another helix by an amount equal to the displacement of said I picture lines first mentioned.

3. A transmitting apparatus comprising, in

' combination, a mirror drum having a plurality of reflecting surfaces arranged in a plurality of helices around the axis of said drum, the reflecting surfaces of one helix being displaced less than the Width of one reflecting surface from the reflecting surfaces of another helix.v

4. A scanning apparatus comprising, in combination, a mirror drum having a plurality of reflecting surfaces arranged in a plurality of helices around the axis of said drum, the reflectingsurfaces of one helix being displaced one-half the width of one reflecting surface from the reflecting surfaces of another helix.

5. A transmitting apparatus comprising, in combination, a mirror drum having a plurality of reflecting surfaces arranged in a plurality of helices around the axis of said drum, the reflecting surfaces of one helix being displaced onethird the Width of one reflecting surface from the reflecting surfaces of another helix.

such that the second reflecting edges of each pair are spaced apart at the same angular distance that said pairs are spaced.

'1. A scanning drum comprising a plurality of substantially flat plates, each of said plates having a straight refl'ecting edge, said plates being arranged in groups with the reflecting edges of each group in alignment and said groups being rotated to form: equal angles between the reflecting surfaces of successive groups, asecondreflecting edge on each plate, the second reflecting edge of at least one plate of each group bearing an angle to the first reflecting surface of that plate equal to'the angular spacings between groups.

8. A scanning device comprising a drum, a group of reflecting surfaces arranged in equally spaced relation from end to end of said drum and in a helix at equal angles around said drum, a second group of the same number of reflecting surfaces arranged in equally spaced relation from end to end of said drum and in a helix at the same equal angles around said drum, the corresponding reflecting surfaces of the two groups being axially displaced avclistance not greater than one-half the axial spacing of adjacent refleeting surfaces in the same group.

9. A scanning device comprising a drum, a

group of long, narrow reflecting surfaces equally spaced from end to end of said drum and arranged at equal angles in a helix passing a predetermined angular distance around the axis of said drum, a second group of long, narrow reflecting surfaces spaced from end to end of said drum with the same equal spacing as said first group and arranged at equal angles in a helix passing through the same angular distance around the axis of said drum as said first reflecting surfaces, the first reflecting surface of each of said groups having substantially the same angular spacing from the last reflecting surface of the othergroup I as the angular spacing between adjacent reflecting surfaces, corresponding reflecting surfaces of the two groups being axially displaced a distance substantially equal to one-half the axial displacement between adjacent reflecting surfaces in the same group. a

' ROBERT HARDING, JR. 

